The invention relates to apparatus and methods for cutting web materials and particularly to such materials which are movable through the apparatus prior to and subsequent such cutting. Even more particularly, the invention relates to cutting web materials that will eventually form part of a circuitzed substrate such as a printed circuit board. One particular example of such material is what is referred to in the industry as dry film photoresist.
As is known, the manufacture of circuitized substrates such as those referred to in the industry as printed circuit (or wiring) boards typically involves the precisioned alignment of individual sheets of web material known as photoresist film. Such material when cut into individual sheet form, is then typically bonded to a base substrate which includes a dielectric material (e.g., a fiberglass-reinforced epoxy resin material commonly referred to in the industry as xe2x80x9cFR4xe2x80x9d material) having a layer of electrically conductive material (e.g., thin copper) bonded thereto. These members are then laminated together to form a core structure or the like which is then subjected to photolithographic processing to form the desired circuitry on the conductive layer. This resulting structure may then be populated with desired electronic devices (e.g., semiconductor chips, capacitors, resistors, etc.) to form a printed circuit (or wiring) board. Alternatively, this resulting structure may then be aligned, with other, similar structure and laminated to form a multilayered structure when then may be populated, etc. during subsequent processing.
Photoresists are categorized as negative or positive and may be obtained in solid (dry film) or liquid form for application onto the aforementioned dielectric-conductor subassembly. The use of liquid (also called xe2x80x9cwetxe2x80x9d) photoresist processing presents several problems to the manufacturer, including the need for complex controlling of liquid material flow, along with relatively complex mechanisms (e.g., rollers) for handling same. The use of dry photoresist films eliminates many of these difficulties and such films are thus more desirable from a manufacturing standpoint. It will be understood from the following that the invention is particularly directed to use of dry film photoresist materials, including those applied to an underlying dielectric-onductive layer subassembly using adhesive or the like. It is to be understood, however, that the invention is not limited to such materials, as it is readily possible to utilize the unique teachings of this invention with several other different varieties of xe2x80x9cdryxe2x80x9d materials (including, e.g., paper, photographic film, etc.).
There are several known methods and apparatus for handling web material including photoresist films, as described and illustrated in the following U.S. Letters Patents:
U.S. Pat. No. 3,595,564xe2x80x94De Young
U.S. Pat. No. 3,680,418xe2x80x94Phillips
U.S. Pat. No. 3,703,116xe2x80x94Doll
U.S. Pat. No. 3,728,921xe2x80x94Vogel
U.S. Pat. No. 3,748,939xe2x80x94Feinstein et al
U.S. Pat. No. 3,888,066xe2x80x94Tabur
U.S. Pat. No. 3,965,785xe2x80x94Johns
U.S. Pat. No. 4,207,667xe2x80x94D""Angelo et al
U.S. Pat. No. 4,772,353xe2x80x94Weiss et al
U.S. Pat. No. 4,919,351xe2x80x94McNeil
U.S. Pat. No. 5,074,178xe2x80x94Shetley et al
U.S. Pat. No. 5,103,703xe2x80x94Littleton
U.S. Pat. No. 5,162,071xe2x80x94Nagafuchi et al
U.S. Pat. No. 5,176,784xe2x80x94Nagafuchi et al
U.S. Pat. No. 5,188,699xe2x80x94Senda
U.S. Pat. No. 5,372,670xe2x80x94Cummings et al
U.S. Pat. No. 5,425,834xe2x80x94Shinohara et al
U.S. Pat. No. 5,456,789xe2x80x94Boucher
Of these, particular attention is directed to U.S. Pat. No. 4,772,353 which specifically describes cutting photoresist webs using cutters (10) which engage the webs prior to board positioning. Attention is also directed to U.S. Pat. Nos. 5,425,834 and 5,456,789 where web materials are roller supplied and cut using various blade structures. Finally, attention is directed to U.S. Pat. No. 5,372,670, which is assigned to the same assignee as the present invention and is incorporated herein by reference. U.S. Pat. No. 5,372,670 defines a system for application of dry film photoresist material which in turn has been supplied from two spaced apart rollers such that the dry film will be positioned on opposite sides of the interim substrate. It is to be understood that the present invention could be utilized with this and similar structures.
A particular method of cutting dry film photoresist material involves the use of rotating, round (pizza-cutter type) cutters which cut the web material at two locations to define the sheet desired for a particular end product (circuit board). Such cutters are considered relatively expensive and maintenance-intensive, often requiring replacement. Such cutters have also proven to have a deleterious effect on the motors used to drive same, often causing motor burn out, thus adding even further to the cost of such assemblies.
It is believed that a cutting apparatus for web material such as dry film photoresist which overcomes the aforementioned disadvantages as well as those found in one or more of the foregoing several patents would represent a significant advancement in the art.
It is, therefore, a primary object of the present invention to provide a new and unique apparatus and method for cutting web material which obviates the various disadvantages cited herein and otherwise discernible from reviewing the foregoing patents.
It is another object of the invention to provide a method and apparatus for cutting dry film material such as photoresist which is then almost immediately deposited on an underlying substrate such as described above.
It is still another object of the invention to provide such a method and apparatus which can be produced and operated in a relatively inexpensive manner (e.g., by assuring ready repair and replacement of various parts thereof if needed).
In accordance with one embodiment of the invention, there is provided an apparatus for cutting web material which comprises a blade holder adapted for being reciprocally moved in a second direction substantially perpendicular to the first direction of movement of the web material, and first and second blades angularly positioned on the blade holder relative to one another and to the second direction of reciprocal movement of the blade holder, each of the blades adapted for engaging the web material in a reverse manner at a predetermined angle during at least part of the reciprocal movement.
In accordance with another embodiment of the invention, there is provided a method for cutting web material wherein the method comprises the steps of cutting the web material at a first location by engaging the web material with a first blade in a reverse manner wherein the blade moves in a second direction substantially perpendicular to the first direction of movement of the web material, and thereafter cuing the web material at a second location spaced from the first location by engaging the web material with a second blade also in a reverse manner wherein the second blade moves in a third direction also substantially perpendicular to the first direction and substantially opposite the second direction.
In accordance with still another embodiment of the invention, there is provided a method for making a printed circuit board wherein the method comprises the steps of providing a substrate including a dielectric having a conductive layer thereon, providing a length of web material, cutting the web material at a first location by engaging the web material with a first blade in a reverse manner wherein the blade moves in a second direction substantially perpendicular to the first direction of movement of the web material, thereafter cutting the web material at a second location spaced from the first location by engaging the web material with a second blade also in a reverse manner wherein the second blade moves in a third direction also substantially perpendicular to the first direction and substantially opposite the second direction. The cutting results in a predetermined length of said web material which is then positioned on the substrate. An electrical circuit is then formed from the conductive layer.